Medical Biology Institute has undergone rapid growth since its inception in March 1982. The research interests of our scientific staff encompass nearly all aspects of Immunology and most of the projects rely greatly upon irradiated animals and/or irradiated cells. The various research projects, which are mainly funded by research grants from the National Institutes of Health, (documented in further detail in Section II) are jeopardized by the upcoming loss of the particular piece of instrumentation which this grant proposal is intended to replace. We request that this proposal be funded so that we may carry on with our important and wide-ranging research.